1. Field of the Invention
The present invention is directed to image forming apparatus, and method and computer program product for image forming.
2. Description of the Related Art
Electrophotographic apparatuses, such as color copiers and color printers, adopting color printing are increasing in number to meet demands of market. Because color printing is desired to achieve printing speed comparable to that of monochrome printing particularly these days, tandem image forming apparatus that includes a photosensitive member and a developing device for each of multiple colors and forms a color image by forming a single-color toner image on each of the photosensitive members and sequentially transferring the single-color toner images onto transfer paper has become mainstream.
In recent years, a number of techniques related to image forming apparatuses that perform full-color printing by using both a direct transfer system and an indirect transfer system have been disclosed (Japanese Patent Application Laid-open No. 2006-85138, for example).
Such an image forming apparatus typically performs full-color printing by using two belts, or specifically an intermediate transfer belt and a transfer-paper conveying belt. If the two belts moving at different conveyance velocities are brought into contact with each other in a transfer operation, color misregistration (misalignment) in the sub-scanning direction can disadvantageously occur.
It is also disadvantageous that if the belts moving at different conveyance velocities come into contact, it can result in fast development of wear of the belts or abrasions on the belts.